stuck again with percentage question

Question

A scientist has two solutions, which she has labeled Solution A and Solution B. Each contains salt. She knows that Solution A is 65% salt and Solution B is 80% salt. She wants to obtain 150 ounces of a mixture that is 70% salt. How many ounces of each solution should she use?

Answer 1

65 mixed with 80 to get 70 means about 2 times as much of 65 as 80. 65 is closer to 70

65 is within 5 of 70. 80 is within 10 of 70. 10 is twice 5. You need twice as much 65 as 80.

150 of 80 divided in a 1:2 ratio means 1/3 is 80 and 2/3 is 65

or 50 ounces of 80% mixed with 100 ounces of 65% yield 150 ounces of 70%

Or

80X + 65(150-X) = 70(150)

80X -65X = 5(150)

15X =15( 50)

X =50 ounces of 80%

150-X = 150-50= 100 ounces of 65%